1. Field of the Invention
The present invention relates to a transporting apparatus for easily moving machine tools and work tools such as an arm of an industrial robot and the like.
2. Description of the Related Background Art
Such a kind of conventional technique has been disclosed in, for instance, JP-B-11209.
As will be obviously understood from FIG. 1 in the above official gazette, the above conventional technique is constructed in the following manner. That is, a pair of two right and left track rails which extend in parallel so as to be away from each other in the vertical direction are arranged in the horizontal direction. A pair of track tables are arranged at the upper and lower positions of the track rails. Track grooves are formed on both side surfaces of the track rails and a bearing main body. A relative free sliding apparatus is arranged between the upper and lower track rails through a number of balls inserted between those opposite track grooves. The upper and lower track tables can be mutually, freely, and rectilinearly moved.
However, in the above conventional technique, since the upper and lower track rails are come into engagement by only the ball bearing, the upper and lower track tables are not interlocked. Therefore, there is a drawback such that in the relative movement, there is no regularity of the positional relations among the bearing main body, the fixed table, and the movable table.
Thus, in the worst case, for instance, when the slide resistance between the fixed table and the bearing main body is fairly larger than that between the movable table and the bearing main body, if the movable table is moved, the positions of the fixed table and bearing main body do not change but only the movable table slides. In a state in which the movable table moved to the midway of the maximum stroke, for instance, by about 1/4 thereof, the main body reaches the end portion of the movable table. There is a problem such that the distortion of the front edge portion of the movable table in such a state becomes maximum.
To solve the above problems, in addition to an apparatus to drive the movable table, it is necessary to additionally provide an apparatus to control the position of the bearing main body. There is also a problem of an increase in costs.